Electric switch



Aug. 23, 1932. r. T. GREENWOOD ELECTRIC SWITCH Filed July 1, 1930 2 Sheets-Sheei 1 -23,1932 T/T. GREENWOOD 1,813 388 ELECTRIC SWITCH 'jnvgnior:

Patented Aug. 23, 1932 UNITED STATES PATENT OFFICE TALMA T. GREENWOOD, OF EAST TEMPLETON, MASSACHUSETTS, ASSIGNOR TO CONDIT ELECTRICAL MANUFACTURING CORPORATION, OF SOUTH BOSTON, MASSACHUSETTS,

A CORPORATION OF MASSACHUSETTS ELECTRIC SWITCH Application filed July 1, 1930. Serial No. 485,128.

This invention relates to electric switches. One of the objects of the invention is to surround one of the separable arcing members of an electric switch with a conical blast of in 5 sulating fluid, as air or oil, the blast being an- 10 electric arc, and the re-establishment thereof,

after it has become extinguished.

A further object is to have the conical blast combine into a cylindrical blast that is directed onto the other arcing members so as to provide a definite channel for the arc, without the use of mechanical barriers.

Another object of the invention is general- 1y to im rove the construction and operation of electric switches.

Fig. 1 is a side elevation partly in section of an electric switch embodying the present invention, only those parts necessary for the understanding of the invention being illustrated.

- 2 is a front elevation of the switch of Fig. 1.

Fig. 3 is an enlarged detail of the cooperating stationary and movable arcing members,

the stationary arcing member being in sec- Fig. 4 is a sectional detail ofa modified form of stationary arcing members.

The switch herein shown as embodying the invention comprises a supporting frame 10 which supports a pair of stationary switch members 12 each including an insulating bushing 14 and a conducting stud 16. A movable switch member cooperates with the stationary switch member and comprises a conducting bridging member 18 having at itsopposite ends a air of upstanding and preferably resilient y-supported contact or arcing members 20. The bridging member is secured to the lower end of an insulating lifting rod 22. the upper end of which is connected with suitable operating mechanism.

As herein shown, the upper end of the lifting rod is pivotally supported at one end of a guide link 24 the other end of which link is pivoted to the upper end of a'link 2.6, the

lower end of said link being pivoted to the supporting frame 10. An operating lever 28 is pivoted at oneend to the supporting frame andat its other end is pivoted to the guide link 24. An operating toggle 30 is connected to said operating lever and is operated by a rod 32 to open and close the switch.

Each stationary switch member is provided with a stationary contact or arcing member 34, see especially Fig. 3, that is preferably in the form of a relatively heavy cylindrical block that is screw-threaded on the lower end of the stud 16 and is locked in adjusted position thereon by the lock nut 36.

In accordance with this invention, means is provided to completely surround said arcing member with a blast of arc extinguishing fluid so that the blast or stream completely isolates the stationary arcing member from the cooperating movable arcing member 20 and thus interposes an imperforate moving insulating fiuid barrier between the two contact members. To this end, the stationary switch member is provided with an annular nozzle 38 which surrounds the stationary arcing member and directs a continuous annular conical stream of fluid such as air around and under the contact face of the arcing member. The nozzle consists of an inner annular insulating tube 40 and radially spaced therefrom an outer annular insulating tube 42. The tube 40 has an inclined or conical bottom face 44 and the tube 42 has an inclined conical face 46 which confronts and is spaced from the face 44 and thus provides an inclined or conical passage 48 between the two, which passage is circumferentially continuous and preferably is of constant width. The exit of said passage is such that a blast of fluid issuing therefrom passes under and preferably close to the arcing face of the arcing member 34 and meets under the arcing face in the axial line of the switch member. The two tubes 40 and 42 are secured, as cemented, to an annular flange 50 tion of the insulating bushing 14 above the arcing member 34. The flange 50 and plate 52 have a fluid passage 58 therethrough which is in register with the fluid passage 60 in the flange 56. A pipe 62 is in communication with said passage and admits an arc quenching fluid at an elevated pressure into the bowl 64 of the nozzle passage 48. The pipe 62 of the two stationary switch members are connected by tubes 66 of insulating material to a conductor 68 which communicates with a port in a valve chamber 70 carried by the supporting frame 10. A second pipe 7 2 communicates with the second port of the valve chamber and extends to a tank or other supply 74 of arc extinguishing fluid under the elevated pressure. The switch herein shown is arranged to supply a blast of insulating fluid only during the time of circuit interruption or during the time that the movable switch member is moving between switch closed and open positions whereby to conserve the supply of are extinguishing fluid. To this end the valve chamber contains a valve 76 that is connected and movable with the switch operating lever 28 so that the pipes 68 and 70 are out of communication both when the switch is closed and when it is fully open and are in communication only when the movable switch member is between these two positions.

The fluid can be of any desired and satisfa'ctory nature. The fluid can be air, under elevated pressure. Air is preferred when the electric switch is of the so-called air-break type. The fluid can also be a liquid as oil under elevated pressure. Oil is preferred when the contact members are immersed and separated in a bath of oil. Other liquids, as pure water, carbon tetrachloride and the like can be employed. Other gases as nitrogen, carbon dioxide, and the like can also be employed. With the arrangement herein shown, the conical blast of fluid is annularly continuous under the stationary arcing member and completely surrounds it so that there is no opening in the fluid stream in which the are can play and maintain itself between the cooperatin arcing members. The fluid stream complete y separates and isolates the two arcing members.

Due to the impact of opposing elemental portions of the conical blast of the fluid, the fluid combines under the stationary contact member into a thick cylindrical vertical stream which flows downward upon the top of the movable arcing member 20, thereby surrolmding said member in the blast and rendering the foot of the are on said arcing member unstable and de-ionizing the around at the same time cooling the arcing member. The conical and cylindrical portions of the fluid blast thus act to confine and direct the are and define its path. In the. modification illustrated in F the stationary arcing member 34a is made conical in configuration to have the function of the insulating tube 40 of Fig. 3 and confronts the conical inner face 46a of the insulating tube 42a so that a conical blast of arc quenching fluid is caused to surround the arcing member and act in the manner above described.

I claim:

An electric switch having separable arcing members, and means which insulates the separated arcing members from each other including means providing a free conical blast of determined thickness of arc extinguishing fluid, said blast being annularly continuous and located in the space between the separated arcing members and being directed inwardly from beyond the arc zone between said arcing members and spaced away from one arcing member so that there is a gas space between the arcing face thereof and said conical blast and being directed toward the other arcing member, said blast being convergent in the space between the arcing members and having such velocity that it penetrates the arc gas formed between said arcing members and combines in said space into a cylindrical jet that is directed toward said other arcing member, and means including said blast which constitutes an insulating barrier between said arcing members and prevents the arc therebetween from occupying the space outside said blast.

In testimony whereof, I have signed my name to this specification.

TALMA T. GREENWOOD. 

